Stabilization of hexamethylditin with 2,6-ditertiary-butyl-4-methyl phenol

ABSTRACT

A STABILIZED INSECTICIDAL COMPOSITION COMPRISING HEXAMETHYLDITIN AND A STABILIZING AMOUNT OF 2,6-DITERTIARYBUTYL-4-METHYL PHENOL.

STABILIZATION F HEXAMETHYLDITIN WITH 2,6-DITERTIARY-BUTYL-4-METHYL PHENOL Herbert Q. Smith, King of Prussia, and Edward Everett atent ice lations are prepared they may be used with excellent results, but after standing for a prolonged period activity decreases and in fact disappears after about 3 months. It has now been found that hexamethylditin may be stabilized so that little or no loss of activity results from storage Devon w assignol's to Pelmwa Corporation 5 'b incor oratin with it a stabilizing amount of 2,6-di- No Drawing- Filed 1968 711834 te i'tiary-b htyl-4-ii1ethylphenol. It is to be understood that 9/00 6 Claims the stabilizing agent may be added directly to the hexa- 424-288 methylditin before formulation or it may be added to the 10 already fornulated solid carrier or concentrate containing t e insectici a com osition. ABSTRACT OF E DISCLOSURE It is not known h bw the stabilizing agent functions in A Stabiliz d insecticidal composition compnsfng P this invention. Although 2,6 di-tertiary-butyl-4-methylmethylditin and a stabilizing amount of 2,6-d1-tert1aryphenol is a known antioxidant, its preparation being y Y P closed in US. Pat. No. 2,428,745, related antioxidants and antiozonants are not efiective in stabilizing hexamethlditin.

The unexpected high activity of hexamethyldifin as an y The stabilizing amount of agent which will be used in insecticide is disclosed and claimed in application Ser. the f r ulatio is not critical, but il generally b i N filed 31, 1966 and Which issued as the order of from about 0.5% to about 10% by weight U Pat 3,400,202 p 1968' AS with other of the total formulation. Preferably from 1 to 5% by insecticides, hexamethylditin may be formulated into 50- i h ill b d lution of dispersion Concentrates of the active agent in In order to illustrate the invention the following tests one or more common solvents normally used as a carrier. were i d For example, heXamethylditin y be dissolved in Origami; Formulations comprising a liquid carrier, hexamethylliquids Such as ketofles (@06110116, methyl ethyl ketone, ditin as active insecticide, and a surfactant of the alkyl e amides (dimethylacetamide. dimethylformamide. aryl polyether alcohol type (Triton X155) were prepared aromatic hydrocarbons such as benzene, toluene. and stored at room temperature over a period of time in xylene, alcohols and giycols, Cellosolve (trademark), and one test and, in the second test, subjected to accelerated various oxygen containing industrial organic solvents and aging by storing at 130 F. Activity of formulations was the like. Dispersions of the active agent may be then v determined by determining the percent kill of mosquito prepared by diluting the organic solvent concentrate syslarvae at 0.1 p.p.rn. The test used was that disclosed in tern with Water in the presence or absence of a surface Example I of Ser. No. 538,991, now U.S. Pat. No. 3,400,-

active agent. 202. The following table indicates the results obtained.

TABLE I Percent Percent kill of mosquito larvae tested at 0.1 p.p.m., stored at- Hexa- Test Time of methylagent, Surfactant, storage, Room ditin BHT 1 Xylene Triton X 165 days temperature 2 130 Fl 10 0 s5 1 88 0, 0 0, 0 10 1 as 1 as 95, 90 100, 90 10 5 s4 1 88 so, so 90, 9s 10 10 79 1 88 90, 75 75, 90 10 10 79 1 118 90, 70 90,100 2,6di-tertiary-butyl-4-methylphenol is often referred to as BHT, meaning butylated hydroxytoluene.

2 Two replicates.

Likewise, hexamethylditin may be formulated as dusts and powders where the inert carrier is a clay such as fullers earth, china, clay, kaolin, attapulgite, bentonite, and related aluminum silicates. Other finely divided inorganic solids may be used and in general these will have a par- As can be seen from the above data, BHT is surprisingly effective in maintaining activity of the insecticide.

The following table indicates the failure of various other known antioxidants as stabilizers.

1 Propyl gallate (10). 2 Butylated hydroxyanisole (l0). 3 Dihydrocoumarln (l0).

ticle size below 200 mesh and contain from about 0.5

As can be seen from the data, none of the above antito 25% by weight active agent. These formulations are oxidants or antiozonants are as effective as BHT and even sprayed or dusted in the usual manner onto the particular substrate to be protected against insect attack.

It has been observed, however, that when such formuthe related butylated hydroxy anisole (BHA) which differs only by having a methoxy group instead of hydroxy is not effective as a stabilizer.

In another evaluation, a solid carrier formulation was prepared with and without BHT and its activity determined after storage. The following table indicates the results of these tests:

As can be seen from Table III the BHT is quite effective in retaining the activity of the hexamethylditin.

The preferred application of the invention will be to organic solvent concentrates of hexamethylditin which are stored and made into aqueous dispersions just prior to use. In preparing such concentrates it is also preferable to use components which are essentially devoid of Water, since it has been observed that the presence of water may have a detrimental effect.

Another unexpected and desirable effect obtained from the stabilized and insecticidal compositions of the invention is decreased phytotoxicity when the insecticidal composition is used on plants. The unstabilized material when applied to plants frequently causes a phytotoxic effect. An insecticide for plant use should, of course, not be injurious to the plants on which it is sprayed. It has been observed that the stabilized insecticidal compositions of this invention cause little or no phytotoxic effects and this is illustrated with the following data:

TABLE IV' [Cotton plants sprayed at rate of 1 pound per acre with xylene formulation containing 10% hexamethylditin and 1% surfactant (Triton X)] It will be understood from the above description and examples of the invention that numerous variations and changes may be made without departing from the spirit and scope of the invention.

We claim:

1. A stabilized insecticidal composition comprising hexamethylditin and a stabilizing amount of 2,6-di-te1'tiarybutyl-4-methyl phenol.

2. A stabilized insecticidal composition comprising hexamethylditin, an inert insecticidal carrier and a stabilizing amount of 2,G-ditertiary-butyl-4-methyl phenol.

3. A composition as in claim 2 wherein the inert insecticidal carrier is an inert, organic solvent.

4. A composition as in claim 2 wherein the inert insecticidal carrier is an inert inorganic solid.

5. A composition as in claim 2 wherein the stabilizer is present in an amount from about 0.5 to about 10% by weight of the total composition.

6. A composition as in claim 4 wherein the inert inorganic solid has a particle size below 200 mesh.

References Cited UNITED STATES PATENTS 7/1963 Sprinkle et al. 424346 9/1968 Smith et a1. 424-288 US. Cl. XJR. 260429.7 

